diff --git a/os_brick/encryptors/luks.py b/os_brick/encryptors/luks.py
index 0faae28c7..d0f5ad48f 100644
--- a/os_brick/encryptors/luks.py
+++ b/os_brick/encryptors/luks.py
@@ -119,6 +119,7 @@ class LuksEncryptor(cryptsetup.CryptsetupEncryptor):
         # Enter new passphrase for key slot:
         # Verify passphrase:
         self._execute('cryptsetup', 'luksAddKey', self.dev_path,
+                      '--force-password',
                       process_input=''.join([mangled_passphrase, '\n',
                                              passphrase, '\n', passphrase]),
                       run_as_root=True, check_exit_code=True,
diff --git a/os_brick/tests/encryptors/test_luks.py b/os_brick/tests/encryptors/test_luks.py
index 191acbc30..c1e12798b 100644
--- a/os_brick/tests/encryptors/test_luks.py
+++ b/os_brick/tests/encryptors/test_luks.py
@@ -227,6 +227,7 @@ class LuksEncryptorTestCase(test_cryptsetup.CryptsetupEncryptorTestCase):
                       root_helper=self.root_helper, run_as_root=True,
                       check_exit_code=[0, 4], attempts=3),
             mock.call('cryptsetup', 'luksAddKey', self.dev_path,
+                      '--force-password',
                       process_input=''.join([fake_key_mangled,
                                              '\n', fake_key,
                                              '\n', fake_key]),